Individual training
This kind of training makes all players train, but it isn't as effective as the others. That's why it's not a good choice for primary training, unless you have just started your youth academy. An argument which backs this kind of training is that, if you have many "relevant" players, all of them will train, and the "important" players will also train something useful. You can choose what each player will train when you place the players on your lineup. For example, a midfielder may train playmaking, often defending or passing, and sometimes winger, but never scoring or goalkeeping. Another reason to choose individual training is that you may get many more messages about a player having reached their skill limit. However, many times a player will have to train a skill which he can't develop any further, and an important player may have reached his limit without notice. In other words, this training may be better or worse than the others as a secondary training, depending on the risk that an important player may have reached his limit in the main training.